Such a fuel tank is known from the European Patent No. 0 320 643. The fuel tank is provided with a trapping device, arranged in its filler neck, for collecting fuel vapors when refueling. The filling flap is transferred into the open position, as soon as the filling pipe of a gas hose nozzle is inserted into the filler neck. In the previously known fuel tank, the filling flap at the same time forms the valve body of the valve, which is arranged between the fuel tank and an active carbon filter for sealing the vent line.